首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 156 毫秒
1.
LetN, be von-Neumann-Algebras on a Hilbert space , a comon cyclic and separarting vector. Assume to be cyclic and separating also forN . Denote byJ , J N the modular conjugations to (, ), and N the associated modular operators. If and these data define in a canonical way a conformal quantum field theory in a cricle. Conversely, the chiral part of a conformal quantum field theory in two dimensions always yields such data in a natural way.Partly supported by the DFG, SFB 288 Differentiageometrie und Quantenphysik  相似文献   

2.
A variety of rigorous inequalities for critical exponents is proved. Most notable is the low-temperature Josephson inequalitydv +2 2–. Others are 1 1 +v, 1 1 , 1,d 1 + 1/ (for d),dv, 3 + (for d), 4 , and 2m 2m+2 (form 2). The hypotheses vary; all inequalities are true for the spin-1/2 Ising model with nearest-neighbor ferromagnetic pair interactions.NSF Predoctoral Fellow (1976–1979). Research supported in part by NSF Grant PHY 78-23952.  相似文献   

3.
Zusammenfassung Es werden Ergebnisse beschrieben über die Temperaturabhängigkeit: der kritischen Schubspannung 0, des Verfestigungskoeffizienten A , im BereichA der Verfestigungskurve; des Verfestigungskoeffizienten B im BereichB, der Längea A des BereichsA und der Schubspannung A am Ende des BereichsA. Die kritische Schubspannung wächst im Temperaturbereich 225–344°K linear mit abnehmender Temperatur. Der Temperaturverlauf des Verfestigungskoeffizienten A , stimmt überein mit älteren Messungen an h.k.p. Metallen. Ähnlich verhält sich der Verfestigungskoeffizient B . Die Schubspannung am Ende des BereichsA wird durch thermisch aktivierte Vorgänge beeinflußt. Der BereichA verkürzt sich im Temperaturbereich 0–85°C linear mit zunehmender Temperatur. Temperaturwechselversuche zeigen, daß im BereichB thermisch irreversible Änderungen in der Versetzungsstruktur auftreten.
: 0, A , B , A A . 226 344°K . A . B . . 0–85°C . , .


Herrn Dr. F. Kroupa und Ing. B. esták bin ich für das Durchlesen des Manuskripts sowie wertvolle Hinweise zu Dank verpflichtet. Mein besonderer Dank für zahlreiche fruchtbare Diskusionen und Anregungen gilt Herrn P. Kratochvíl. Herrn Prof. Dr. A. Seeger danke ich ganz besonders für Kritik des Manuskripts und wertvolle Ratschläge.  相似文献   

4.
, . 20–1000 keV Sc, Fe, Cu, Mo, Cd La.
The radiative capture of a neutron on Sc, Fe, Cu, Mo, Cd and La nuclei
The energies and intensities of the transitions of a compound nucleus, produced by the capture of a neutron, were measured by means of a single-crystal scintillation spectrometer. The region of energies 20–1000 keV was measured on Sc, Fe, Cu, Mo, Cd and L a nuclei.
  相似文献   

5.
. , , , . .
The theory and structure of the temperature image
The paper describes the theory of the formation of a temperature image when there are large temperature differences and introduces the concept of temperature distortion of an image. It also deals with the geometrical distortion of the temperature image by the longitudinal thermal conductivity of the receiver layer and gives a solution of the corresponding differential equation of the temperature image for the case of a general linear line test and general circular concentric test. Equations are derived for the temperature distributions of the temperature images of some optical lineated and circular test objects and their geometrical distortion due to the thermal conductivity of the receiver layer is investigated.
  相似文献   

6.
As in Part I of this paper, we consider the problem of the energy exchanges between two subsystems, of which one is a system of harmonic oscillators, while the other one is any dynamical system ofn degrees of freedom. Such a problem is of interest both for the realization of holonomic constraints of classical mechanics, and for the freezing of the internal degrees of freedom in molecular collisions. The results of Part I, which referred to the particular case =1, are here extended to the more difficult case >1. For the rate of energy transfer we find exponential estimates of Nekhoroshev's type, namely of the form exp (*/)1/a , where is a positive real number giving the size of the involved frequencies, and * anda are constants. For the particularly relevant constanta we find in generala=1/ however, in the particular case when the frequencies are equal (collision of identical molecules), we finda=1 independently of , as conjectured by Jeans in the year 1903.  相似文献   

7.
( ) , . , . [1] , , .
Partially inserted block in square lattice
The paper gives a theory of the partially inserted block (control rod) in a reactor of finite height, consisting of a square lattice of fuel blocks and a moderator. The partially inserted block replaces the block of the original lattice which was located in the axis of cylindrical symmetry of the reactor. The results obtained agree with the relations for a homogeneous medium in paper [1] and are thereby justified for homogeneized reactors.
  相似文献   

8.
9.
The observation of double quantum transitions on three kinds of free radicals (DPPH, DPANO, ultramarine) at temperatures of liquid nitrogen is described. Signals having an absorption and emission character were observed in the 12-5 MHz–18 MHz frequency band in the direction parallel to the external magnetic fieldH 0 and their dependence on different parameters was studied.Bloch equations were solved for two mutually perpendicular high-frequency fields and expressions were found for the components of dynamic susceptibility in theH 0 direction. The experiments agree with theory.The possibility of using double quantum transitions for measuring relaxation times is discussed.
(DPPH, DPANO, ) . 12,5MHz–18MHz H 0, ; . H 0. . .
  相似文献   

10.
11.
The method of sliding photomultipliers was used to study the connection between two forms of the positive column in oxygen — the so-called low-gradientT-form and the highgradientH-form — and the presence of moving striations in the positive column. It was shown that in theT-form of a positive column striations are always present which move from the cathode to anode with a velocity of several thousand metres/sec. The highgradient form of theH-positive column, on the other hand, is not striated. The non-single-valuedness of the value of the longitudinal electric field in a discharge in oxygen is thus explained by the presence or absence of phenomena of a time variable character.
— - H - — . , - , /. , , . , , , .
  相似文献   

12.
A theory is given of a new structure produced when demagnetizing uniaxial single crystals (e.g. magnetoplumbite) in a field normal to thec axis. The experimental results fully support the theory on the assumption that domain structures produced under normal conditions are metastable. Methods are given by which stable structures can be prepared from such metastable ones. On the basis of these results opinions are expressed as to the nucleation of plate and honeycomb structures, produced either by reducing the field from saturation or by cooling below the Curie point.
, (, ) , c. , , , , , . , . , .


In conclusion the authors would like to thank C. Novák from the Institute of Technical Physics, Czechoslovak Academy of Sciences, for checking the calculation of the harmonic analysis and Z. Málek and J. Eousek for carefully reading the paper and for valuable remarks.  相似文献   

13.
We demonstrate with the example of Cahn-Hilliard dynamics that the macroscopic kinetics of first-order phase transitions exhibits an infinite number of constants of motion. Moreover, this result holds in any space dimension for a broad class of nonequilibrium processes whose macroscopic behavior is governed by equations of the form /t = W(), where is an order parameter,W is an arbitrary function of , and is a linear Hermitian operator. We speculate on the implications of this result.  相似文献   

14.
Qj , i 4 ISb, - N , –180° +400°C. , ISb zi, - ; -m n =3,6. 10, n . menem , , - .eue . - - .  相似文献   

15.
Different models of luminescence centres are discussed on the basis of measurements of the composition of ZnS monocrystal photo-luminescence in different polarizations and temperature dependence of the degree of polarization. Those of the models submitted by Birman, which assume the polarization to be due to the different force of the oscillators for transitions withEc andEc, or models assuming luminescence polarization to be due to the orientation of the luminescence centres, agree with the results of experiments, i.e. the temperature independence of the degree of polarization and the conformable spectral composition of both polarizations. It is also shown that measurements made up to now of the degree of polarization must be taken as orientational as a consequence of the depolarizing influence of the diffused rays of luminescence on its value.
ZnS: Cu
ZnS , . , . . , , , E E, , . , , - .
  相似文献   

16.
17.
Double beta decay is discussed in relation to parity non-conservation. Two possible ways of neutrino-less double beta decay (allowed and forbidden) are investigated and the half-life of decay is calculated. For allowed transitions we obtain for Ca48 an estimatedT1/2=2×1019 years. The negative results of the experiments by Lukjanov et al., who give the valueT1/2=0.7×1019 years for the lower limit of the half-life of double beta decay of Ca48, cannot therefore be regarded as a definitive solution of the question, whether the neutrino is a Dirac or Majorana particle. Further study of double beta decay, aimed at finding higher values of the lower limit of half-life, are of considerable importance for theory.
-
- . - ( ) . 48 T1/221019 . - . [1] ( - 48 T1/2 0,71019 ), , . - .


In conclusion the author thanks Prof. I. S. apiro for suggesting this work and help in elaborating it.  相似文献   

18.
19.
The aim of this note is to show that the affine Lie algebraA 1 (1) has a natural family , ,v of Fock representations on the spaceC[x i,y j;i andj ], parametrized by (,v) C 2. By corresponding the highest weight , of , to each (,), the parameter spaceC 2 forms a double cover of the weight spaceC0C1 with singularities at linear forms of level –2; this number is (–1)-times the dual Coxeter number. Our results contain explicit realizations of irreducible non-integrable highest wieghtA 1 (1) -modules for generic (,v).  相似文献   

20.
The positron lifetime and DSC measerments for EBBA and DOBAMBC have been made with heating and cooling clycles. The experimental results show that a shorter lifetime (1) is essentially independent of temperature while the longer lifetime (2) and the intensity (I 2) change abruptly double or triple with temperature. Consequently, the EBBA has only nematic phases while the DOBAMBC has two liquid-crystalline phases (smectic C* and smectic A) with transition temperatures as follows: for EBBA, solid nematic (304.5 K), nematic isotropic (356.5 K), isotropic nematic (356.5 K), nematic solid (301 K); and for DOBAMBC, solid smectic C* (346 K), smectic C* smectic A (357.5 K), smectic A isotropic (389 K). These critical temperatures are in accordance with the transition temperatures measured by DSC. In addition, the difference in the solid-nematic transition temperature in the heating and cooling cycles was also observed. A discussion about the correlation of the observed changes in lifetime (2) with the changes in molecular orientational order (S) and dielectric anisotropy () is presented.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号